AB0043 THE IMPACT OF ANTI-Ro52 ANTIBODIES ON THE EXPRESSION OF ANTIVIRAL RESPONSE-RELATED GENES – PRELIMINARY STUDY
Authors: A. Opinc, J. Sarnik, Z. Łukasik, J. Makowska
Journal: Annals of the Rheumatic Diseases (2022)

Background Ro52, also known as TRIM21, is an essential agent of the innate host defence, especially of the antiviral responses 1 . It was found to be induced by type I and II interferons. Due to its activity of E3 ligase, TRIM21 is involved in the ubiquitination of several IFN regulating factors (IRFs) 2 . Ro52 enables antibody-dependent intracellular neutralization as a high-affinity Fc immunoglobulin receptor 1 . The auto-ubiquitination of the TRIM21-related complex induces signalling pathways with the production of pro-inflammatory cytokines 1 . Anti-Ro52 autoantibodies are found in versatile autoimmune conditions. The hypothesis of our project assumes that viral infections in genetically susceptible individuals trigger overexpression of Ro52, followed by the production of autoantibodies, which suppress its function as the negative regulator of type I interferon responses, leading to enhanced production of proinflammatory agents that uphold autoimmune process. Objectives To compare the expression of antiviral response-related genes in patients with anti-Ro52 autoantibodies and healthy volunteers in order to assess the significance of anti-Ro52 in the antiviral defence. Methods Anti-Ro52+ patients, hospitalized at the Department of Rheumatology, Medical University of Lodz or treated in the united outpatient clinic were recruited. 19 patients with anti-Ro52 antibodies were included in the study group (mean age: 54,2 years, F:M ratio 14:5). Among them, 5 patients were diagnosed with primary Sjogren syndrome, 5 with idiopathic inflammatory myopathies, 4 with systemic lupus erythematosus, 1 with rheumatoid arthritis, 3 with overlapping syndromes and 1 was undergoing diagnosis of connective tissue disease at the time of the recruitment. Data on the diagnosis, clinical symptoms and laboratory results were collected from the patients and the available medical records. 10 healthy individuals without autoimmune disorders were recruited to the control group. Whole blood samples were collected from both anti-Ro52+ patients and healthy controls, PBMC were isolated using Biocoll reagent. RNA was isolated from each sample with RNeasy and cDNA synthesis was performed by RevertAid™ H Minus First Strand cDNA Synthesis Kit. The mRNA expression levels of TRIM, IRF3, IRF5, IRF7, NFκB, RIG-1, MDA5 genes were examined by quantitative real-time PCR with TaqMan™ Universal PCR Master Mix according to the manufacturer’s instructions. The expression levels of genes relative to that of GAPDH were calculated by delta Ct (ΔCt). The ΔCt value is the Ct value of the target gene subtracted its Ct value of GAPDH, ΔCt = Ct (Gene) − Ct (GAPDH). Therefore, the smaller the ΔCt values, the higher the expression levels of the target mRNA. The Mann–Whitney rank sum test was used to compare the control group and anti-Ro52+ patients. Results The ΔCt values for TRIM, IRF3, IRF5, IRF7, NFkB, RIG-1, MDA5 were found to be lower in the anti-Ro52+ group as compared to the control group, indicating higher mRNA expression of these genes in anti-Ro52+ patients. Statistical significance was reached for all of the examined genes but IRF3. Detailed results are presented in Table 1. Table 1. The ΔCt values for antiviral response-related genes in anti-Ro52+ patients and healthy controls. P – statistical significance Anti-Ro52+ group ΔCt Control group ΔCt p TRIM 4,91 6,64 &lt;0,0001 IRF3 5,70 5,92 0,8482 IRF5 4,45 5,68 &lt;0,0001 IRF7 5,14 6,54 &lt;0,0001 NFκB 4,78 5,66 &lt;0,0001 RIG-1 3,77 4,33 0,0188 MDA5 5,08 6,82 &lt;0,0001 Conclusion Presented results confirm the enhancement of the antiviral defence in anti-Ro52+ patients. As overexpression is observed independently in various connective tissue diseases, impaired response to viral infections via Ro52 pathways could indicate a common trigger factor of autoimmunity. References [1]doi: 10.3389/fimmu.2019.02049 [2]doi: 10.1016/j.jaut.2012.01.014 Disclosure of Interests None declared